Temperature detectors which employ thermistors in operating contact with an environment which is being monitored for temperature has many uses, more particularly in our modern society which is becoming more energy conscious. Protection of the thermistor from that environment, while simultaneously permitting heat transfer on a uniform basis to permit accurate monitoring, is a major concern. This is true particularly when the environment and/or the temperature range is extreme.
When a thermistor is directly soldered onto the inner bottom of a protection tube, the thermistor will be reliably connected to the tube. This, however, is a difficult operation because the silver electrode surface of the thermistor easily reacts with the solder. Moreover, protection tubes are normally formed by cutting and machining metal, which results in a surface which is not completely smooth and uniform. Oxidation can then develop during the use of the device over varying temperature cycles, giving rise to the occurrence of contact resistance.
Accordingly, it is an object of this invention to provide a method for utilizing a thermistor in a protection tube as a sensing device for temperature.
Another object of this invention is to provide a device which is capable of withstanding acyclic temperature changes without damage to the heat transfer apparatus from the protection tube to the thermistor.
Other objects will appear hereinafter.